14 BULLETIN 5-1, U. S, DEPARTMENT OF AGRICULTURE. 



recently acquired and is unimportant. Little salt is now -visible in the Honey Lake 

 Basin. 



On tJie northwest slope of Pea vine Peak there is a small basin about 30 square miles 

 in area which contains a small marsh separated from the headwaters of Long Valley 

 Creek only by a low allu^dal di^dde near the station of Purdy, on the Nevada, Cali- 

 fornia & Oregon Railway. During Quaternary time this small basin undoubtedly 

 drained into Long Valley Creek, and it has therefore no importance to the present 

 inquiry. Its area is included in the above figures for the Honey Lake Basin. 



THE TRUCKEE BASIN. 



The Truckee Basin consisted in Quatemaiy time, as it does now, of the drainage 

 basin of the Truckee River heading in the SieiTas, notably in Lake Tahoe, and empty- 

 ing into the twin lakes Pyramid and Winnemucca. The approach of the river to 

 these lakes is over somewhat dissected alluvium, and the river has flowed at times 

 into the one lake and at times into the other. At the present time it flows into the 

 Pyramid. During the existence of Lake Lahontan the valley of Winnemucca Lake 

 contained a long, narrow arm of water connected with the PjTamid Lake body at its 

 southern extremity, while the northern end of the latter lake joined the water body 

 of the Black Rock Desert. This latter connection was one of the last to be broken 

 when Lahontan disappeared, and it is probable that the Truckee Basin continued to 

 overflow into the Black Rock long after the rest of the Lahontan water bodies had 

 fully separated. The Tinickee River, being headed in a region of higher rainfall in 

 the Sierras has suffered less truncation than the other rivers of the Great Basin and 

 has been able to keep its channel fairly clear. Several tributary valleys have lost 

 their free outward drainage and have become somewhat saline, but they are few and 

 insignificant. In the Lahontan period, however, Pyramid Lake received another 

 considerable tributary which entered it from the west through a gap in the Virginia 

 Range, bringing the drainage of the so-called Winnemucca Valley (which has no rela- 

 tion to Lake Winnemucca). 



This drainage line has entirely decayed, and a large area once tributary to it — the 

 Lemmon Valley, north of Reno — has been cut off by an alluvial divide and become 

 an inclosed basin. whose flat bottom carries a group of playas. This basin has an area 

 of 90 square miles. Just north of this there is the smaller Wai'm Spiings Basin, with 

 an area of less than 20 square miles and separated from the Hungry Valley and the 

 Pyramid Lake drainage by an allu^dal di^^de over 300 feet in height. It is impossible 

 to read clearly the history of this basin from data now at hand. It may be that the 

 divide between it and the Truckee is quite ancient and that the Lahontan period 

 saw it, as now, completely landlocked. However, this question is unimportant, since 

 the basin is too small to have accumulated any considerable salt body. Including 

 the Lemmon Valley, but not the Warm Springs Basin, the total area of the Truckee 

 Basin is 2,975 square miles. 



THE HUMBOLDT-CARSON BASIN. 



The Humboldt-Carson Basin is the core of the Lahontan area. Its present bottom 

 is a great playa covering over 500 square miles and containing in its lowest portion the 

 Carson Sink, a shallow and variable lake of brackish water. South Carson Lake, also 

 on the main playa, is a shallow lake produced by the meanders of the Carson River. 

 A elough connects it with the North Carson Lake, or Carson Sink. The Humboldt 

 River enters the playa from the north through a narrow gap near the station of Parran, 

 on the Southern Pacific Railway. Duiing high water of Lake Lahontan a sand bar 

 was buUt across this gap, behind which Humboldt Lake has been formed. However, 

 overflow has partially cut this bar, and at high-water stages the water of the Humboldt 

 Lake now flows through it and into the Carson Sink. 



